With SuSE 9.2, have you enabled stupid mode - that's not an insult, it's an option in YaST's set up, when you get to the Connection Parameters section. Spontaneous hang-ups are a symptom of not using it.

I'm not too sure exactly where your modem connection is falling over, but are you using kppp as the dialler? If so, before clicking on connect, click on configure then modems then device and set modem device to /dev/tty0 instead of /dev/modem0 if that is what is there now.

Another cause of unexpected terminations like yours is the handshaking (authentication) protocol you have set for your ISP connection. Make sure this is corectly set for your particular ISp - usually PAP/CHAP will do but some require a login script to be run.